/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2024 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_internal.h"

#ifdef SDL_VIDEO_RENDER_OGL_ES2

#include "../../video/SDL_sysvideo.h" // For SDL_RecreateWindow
#include <SDL3/SDL_opengles2.h>
#include "../SDL_sysrender.h"
#include "../../video/SDL_pixels_c.h"
#include "SDL_shaders_gles2.h"

/* WebGL doesn't offer client-side arrays, so use Vertex Buffer Objects
   on Emscripten, which converts GLES2 into WebGL calls.
   In all other cases, attempt to use client-side arrays, as they tend to
   be dramatically faster when not batching, and about the same when
   we are. */
#ifdef SDL_PLATFORM_EMSCRIPTEN
#define USE_VERTEX_BUFFER_OBJECTS 1
#else
#define USE_VERTEX_BUFFER_OBJECTS 0
#endif

/* To prevent unnecessary window recreation,
 * these should match the defaults selected in SDL_GL_ResetAttributes
 */
#define RENDERER_CONTEXT_MAJOR 2
#define RENDERER_CONTEXT_MINOR 0

/*************************************************************************************************
 * Context structures                                                                            *
 *************************************************************************************************/

typedef struct GLES2_FBOList GLES2_FBOList;

struct GLES2_FBOList
{
    Uint32 w, h;
    GLuint FBO;
    GLES2_FBOList *next;
};

typedef struct GLES2_TextureData
{
    GLuint texture;
    bool texture_external;
    GLenum texture_type;
    GLenum pixel_format;
    GLenum pixel_type;
    void *pixel_data;
    int pitch;
#ifdef SDL_HAVE_YUV
    // YUV texture support
    bool yuv;
    bool nv12;
    GLuint texture_v;
    GLuint texture_v_external;
    GLuint texture_u;
    GLuint texture_u_external;
#endif
    GLES2_FBOList *fbo;
} GLES2_TextureData;

typedef enum
{
    GLES2_ATTRIBUTE_POSITION = 0,
    GLES2_ATTRIBUTE_COLOR = 1,
    GLES2_ATTRIBUTE_TEXCOORD = 2,
} GLES2_Attribute;

typedef enum
{
    GLES2_UNIFORM_PROJECTION,
    GLES2_UNIFORM_TEXTURE,
    GLES2_UNIFORM_TEXTURE_U,
    GLES2_UNIFORM_TEXTURE_V,
    GLES2_UNIFORM_OFFSET,
    GLES2_UNIFORM_MATRIX,
    NUM_GLES2_UNIFORMS
} GLES2_Uniform;

static const char *GLES2_UniformNames[] = {
    "u_projection",
    "u_texture",
    "u_texture_u",
    "u_texture_v",
    "u_offset",
    "u_matrix"
};
SDL_COMPILE_TIME_ASSERT(GLES2_UniformNames, SDL_arraysize(GLES2_UniformNames) == NUM_GLES2_UNIFORMS);

typedef struct GLES2_ProgramCacheEntry
{
    GLuint id;
    GLuint vertex_shader;
    GLuint fragment_shader;
    GLuint uniform_locations[NUM_GLES2_UNIFORMS];
    GLfloat projection[4][4];
    const float *shader_params;
    struct GLES2_ProgramCacheEntry *prev;
    struct GLES2_ProgramCacheEntry *next;
} GLES2_ProgramCacheEntry;

typedef struct GLES2_ProgramCache
{
    int count;
    GLES2_ProgramCacheEntry *head;
    GLES2_ProgramCacheEntry *tail;
} GLES2_ProgramCache;

typedef enum
{
    GLES2_IMAGESOURCE_INVALID,
    GLES2_IMAGESOURCE_SOLID,
    GLES2_IMAGESOURCE_TEXTURE_ABGR,
    GLES2_IMAGESOURCE_TEXTURE_ARGB,
    GLES2_IMAGESOURCE_TEXTURE_RGB,
    GLES2_IMAGESOURCE_TEXTURE_BGR,
    GLES2_IMAGESOURCE_TEXTURE_YUV,
    GLES2_IMAGESOURCE_TEXTURE_NV12,
    GLES2_IMAGESOURCE_TEXTURE_NV21,
    GLES2_IMAGESOURCE_TEXTURE_EXTERNAL_OES
} GLES2_ImageSource;

typedef struct
{
    SDL_Rect viewport;
    bool viewport_dirty;
    SDL_Texture *texture;
    SDL_Texture *target;
    SDL_BlendMode blend;
    bool cliprect_enabled_dirty;
    bool cliprect_enabled;
    bool cliprect_dirty;
    SDL_Rect cliprect;
    bool texturing;
    bool texturing_dirty;
    SDL_FColor clear_color;
    bool clear_color_dirty;
    int drawablew;
    int drawableh;
    GLES2_ProgramCacheEntry *program;
    const float *shader_params;
    GLfloat projection[4][4];
} GLES2_DrawStateCache;

typedef struct GLES2_RenderData
{
    SDL_GLContext context;

    bool debug_enabled;

    bool GL_EXT_blend_minmax_supported;

#define SDL_PROC(ret, func, params) ret (APIENTRY *func) params;
#include "SDL_gles2funcs.h"
#undef SDL_PROC
    GLES2_FBOList *framebuffers;
    GLuint window_framebuffer;

    GLuint shader_id_cache[GLES2_SHADER_COUNT];

    GLES2_ProgramCache program_cache;
    Uint8 clear_r, clear_g, clear_b, clear_a;

#if USE_VERTEX_BUFFER_OBJECTS
    GLuint vertex_buffers[8];
    size_t vertex_buffer_size[8];
    int current_vertex_buffer;
#endif

    GLES2_DrawStateCache drawstate;
    GLES2_ShaderIncludeType texcoord_precision_hint;
} GLES2_RenderData;

#define GLES2_MAX_CACHED_PROGRAMS 8

static const char *GL_TranslateError(GLenum error)
{
#define GL_ERROR_TRANSLATE(e) \
    case e:                   \
        return #e;
    switch (error) {
        GL_ERROR_TRANSLATE(GL_INVALID_ENUM)
        GL_ERROR_TRANSLATE(GL_INVALID_VALUE)
        GL_ERROR_TRANSLATE(GL_INVALID_OPERATION)
        GL_ERROR_TRANSLATE(GL_OUT_OF_MEMORY)
        GL_ERROR_TRANSLATE(GL_NO_ERROR)
    default:
        return "UNKNOWN";
    }
#undef GL_ERROR_TRANSLATE
}

static void GL_ClearErrors(SDL_Renderer *renderer)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;

    if (!data->debug_enabled) {
        return;
    }
    while (data->glGetError() != GL_NO_ERROR) {
        // continue;
    }
}

static bool GL_CheckAllErrors(const char *prefix, SDL_Renderer *renderer, const char *file, int line, const char *function)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    bool result = true;

    if (!data->debug_enabled) {
        return true;
    }
    // check gl errors (can return multiple errors)
    for (;;) {
        GLenum error = data->glGetError();
        if (error != GL_NO_ERROR) {
            if (!prefix || prefix[0] == '\0') {
                prefix = "generic";
            }
            SDL_SetError("%s: %s (%d): %s %s (0x%X)", prefix, file, line, function, GL_TranslateError(error), error);
            result = false;
        } else {
            break;
        }
    }
    return result;
}

#if 0
#define GL_CheckError(prefix, renderer)
#else
#define GL_CheckError(prefix, renderer) GL_CheckAllErrors(prefix, renderer, SDL_FILE, SDL_LINE, SDL_FUNCTION)
#endif

/*************************************************************************************************
 * Renderer state APIs                                                                           *
 *************************************************************************************************/

static bool GLES2_LoadFunctions(GLES2_RenderData *data)
{
#ifdef SDL_VIDEO_DRIVER_UIKIT
#define __SDL_NOGETPROCADDR__
#elif defined(SDL_VIDEO_DRIVER_ANDROID)
#define __SDL_NOGETPROCADDR__
#endif

#if defined __SDL_NOGETPROCADDR__
#define SDL_PROC(ret, func, params) data->func = func;
#else
#define SDL_PROC(ret, func, params)                                                            \
    do {                                                                                       \
        data->func = (ret (APIENTRY *) params)SDL_GL_GetProcAddress(#func);                                             \
        if (!data->func) {                                                                     \
            return SDL_SetError("Couldn't load GLES2 function %s: %s", #func, SDL_GetError()); \
        }                                                                                      \
    } while (0);
#endif // __SDL_NOGETPROCADDR__

#include "SDL_gles2funcs.h"
#undef SDL_PROC
    return true;
}

static GLES2_FBOList *GLES2_GetFBO(GLES2_RenderData *data, Uint32 w, Uint32 h)
{
    GLES2_FBOList *result = data->framebuffers;
    while ((result) && ((result->w != w) || (result->h != h))) {
        result = result->next;
    }
    if (!result) {
        result = (GLES2_FBOList *)SDL_malloc(sizeof(GLES2_FBOList));
        result->w = w;
        result->h = h;
        data->glGenFramebuffers(1, &result->FBO);
        result->next = data->framebuffers;
        data->framebuffers = result;
    }
    return result;
}

static bool GLES2_ActivateRenderer(SDL_Renderer *renderer)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;

    if (SDL_GL_GetCurrentContext() != data->context) {
        // Null out the current program to ensure we set it again
        data->drawstate.program = NULL;

        if (!SDL_GL_MakeCurrent(renderer->window, data->context)) {
            return false;
        }
    }

    GL_ClearErrors(renderer);

    return true;
}

static void GLES2_WindowEvent(SDL_Renderer *renderer, const SDL_WindowEvent *event)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;

    if (event->type == SDL_EVENT_WINDOW_MINIMIZED) {
        // According to Apple documentation, we need to finish drawing NOW!
        data->glFinish();
    }
}

static GLenum GetBlendFunc(SDL_BlendFactor factor)
{
    switch (factor) {
    case SDL_BLENDFACTOR_ZERO:
        return GL_ZERO;
    case SDL_BLENDFACTOR_ONE:
        return GL_ONE;
    case SDL_BLENDFACTOR_SRC_COLOR:
        return GL_SRC_COLOR;
    case SDL_BLENDFACTOR_ONE_MINUS_SRC_COLOR:
        return GL_ONE_MINUS_SRC_COLOR;
    case SDL_BLENDFACTOR_SRC_ALPHA:
        return GL_SRC_ALPHA;
    case SDL_BLENDFACTOR_ONE_MINUS_SRC_ALPHA:
        return GL_ONE_MINUS_SRC_ALPHA;
    case SDL_BLENDFACTOR_DST_COLOR:
        return GL_DST_COLOR;
    case SDL_BLENDFACTOR_ONE_MINUS_DST_COLOR:
        return GL_ONE_MINUS_DST_COLOR;
    case SDL_BLENDFACTOR_DST_ALPHA:
        return GL_DST_ALPHA;
    case SDL_BLENDFACTOR_ONE_MINUS_DST_ALPHA:
        return GL_ONE_MINUS_DST_ALPHA;
    default:
        return GL_INVALID_ENUM;
    }
}

static GLenum GetBlendEquation(SDL_BlendOperation operation)
{
    switch (operation) {
    case SDL_BLENDOPERATION_ADD:
        return GL_FUNC_ADD;
    case SDL_BLENDOPERATION_SUBTRACT:
        return GL_FUNC_SUBTRACT;
    case SDL_BLENDOPERATION_REV_SUBTRACT:
        return GL_FUNC_REVERSE_SUBTRACT;
    case SDL_BLENDOPERATION_MINIMUM:
        return GL_MIN_EXT;
    case SDL_BLENDOPERATION_MAXIMUM:
        return GL_MAX_EXT;
    default:
        return GL_INVALID_ENUM;
    }
}

static bool GLES2_SupportsBlendMode(SDL_Renderer *renderer, SDL_BlendMode blendMode)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;

    SDL_BlendFactor srcColorFactor = SDL_GetBlendModeSrcColorFactor(blendMode);
    SDL_BlendFactor srcAlphaFactor = SDL_GetBlendModeSrcAlphaFactor(blendMode);
    SDL_BlendOperation colorOperation = SDL_GetBlendModeColorOperation(blendMode);
    SDL_BlendFactor dstColorFactor = SDL_GetBlendModeDstColorFactor(blendMode);
    SDL_BlendFactor dstAlphaFactor = SDL_GetBlendModeDstAlphaFactor(blendMode);
    SDL_BlendOperation alphaOperation = SDL_GetBlendModeAlphaOperation(blendMode);

    if (GetBlendFunc(srcColorFactor) == GL_INVALID_ENUM ||
        GetBlendFunc(srcAlphaFactor) == GL_INVALID_ENUM ||
        GetBlendEquation(colorOperation) == GL_INVALID_ENUM ||
        GetBlendFunc(dstColorFactor) == GL_INVALID_ENUM ||
        GetBlendFunc(dstAlphaFactor) == GL_INVALID_ENUM ||
        GetBlendEquation(alphaOperation) == GL_INVALID_ENUM) {
        return false;
    }

    if (colorOperation == SDL_BLENDOPERATION_MINIMUM && !data->GL_EXT_blend_minmax_supported) {
        return false;
    }
    if (colorOperation == SDL_BLENDOPERATION_MAXIMUM && !data->GL_EXT_blend_minmax_supported) {
        return false;
    }

    return true;
}

static GLES2_ProgramCacheEntry *GLES2_CacheProgram(GLES2_RenderData *data, GLuint vertex, GLuint fragment)
{
    GLES2_ProgramCacheEntry *entry;
    GLint linkSuccessful;
    int i;

    // Check if we've already cached this program
    entry = data->program_cache.head;
    while (entry) {
        if (entry->vertex_shader == vertex && entry->fragment_shader == fragment) {
            break;
        }
        entry = entry->next;
    }
    if (entry) {
        if (data->program_cache.head != entry) {
            if (entry->next) {
                entry->next->prev = entry->prev;
            }
            if (entry->prev) {
                entry->prev->next = entry->next;
            }
            entry->prev = NULL;
            entry->next = data->program_cache.head;
            data->program_cache.head->prev = entry;
            data->program_cache.head = entry;
        }
        return entry;
    }

    // Create a program cache entry
    entry = (GLES2_ProgramCacheEntry *)SDL_calloc(1, sizeof(GLES2_ProgramCacheEntry));
    if (!entry) {
        return NULL;
    }
    entry->vertex_shader = vertex;
    entry->fragment_shader = fragment;

    // Create the program and link it
    entry->id = data->glCreateProgram();
    data->glAttachShader(entry->id, vertex);
    data->glAttachShader(entry->id, fragment);
    data->glBindAttribLocation(entry->id, GLES2_ATTRIBUTE_POSITION, "a_position");
    data->glBindAttribLocation(entry->id, GLES2_ATTRIBUTE_COLOR, "a_color");
    data->glBindAttribLocation(entry->id, GLES2_ATTRIBUTE_TEXCOORD, "a_texCoord");
    data->glLinkProgram(entry->id);
    data->glGetProgramiv(entry->id, GL_LINK_STATUS, &linkSuccessful);
    if (!linkSuccessful) {
        data->glDeleteProgram(entry->id);
        SDL_free(entry);
        SDL_SetError("Failed to link shader program");
        return NULL;
    }

    // Predetermine locations of uniform variables
    for (i = 0; i < NUM_GLES2_UNIFORMS; ++i) {
        entry->uniform_locations[i] = data->glGetUniformLocation(entry->id, GLES2_UniformNames[i]);
    }

    data->glUseProgram(entry->id);
    if (entry->uniform_locations[GLES2_UNIFORM_TEXTURE_V] != -1) {
        data->glUniform1i(entry->uniform_locations[GLES2_UNIFORM_TEXTURE_V], 2); // always texture unit 2.
    }
    if (entry->uniform_locations[GLES2_UNIFORM_TEXTURE_U] != -1) {
        data->glUniform1i(entry->uniform_locations[GLES2_UNIFORM_TEXTURE_U], 1); // always texture unit 1.
    }
    if (entry->uniform_locations[GLES2_UNIFORM_TEXTURE] != -1) {
        data->glUniform1i(entry->uniform_locations[GLES2_UNIFORM_TEXTURE], 0); // always texture unit 0.
    }
    if (entry->uniform_locations[GLES2_UNIFORM_PROJECTION] != -1) {
        data->glUniformMatrix4fv(entry->uniform_locations[GLES2_UNIFORM_PROJECTION], 1, GL_FALSE, (GLfloat *)entry->projection);
    }

    // Cache the linked program
    if (data->program_cache.head) {
        entry->next = data->program_cache.head;
        data->program_cache.head->prev = entry;
    } else {
        data->program_cache.tail = entry;
    }
    data->program_cache.head = entry;
    ++data->program_cache.count;

    // Evict the last entry from the cache if we exceed the limit
    if (data->program_cache.count > GLES2_MAX_CACHED_PROGRAMS) {
        data->glDeleteProgram(data->program_cache.tail->id);
        data->program_cache.tail = data->program_cache.tail->prev;
        if (data->program_cache.tail) {
            SDL_free(data->program_cache.tail->next);
            data->program_cache.tail->next = NULL;
        }
        --data->program_cache.count;
    }
    return entry;
}

static GLuint GLES2_CacheShader(GLES2_RenderData *data, GLES2_ShaderType type, GLenum shader_type)
{
    GLuint id = 0;
    GLint compileSuccessful = GL_FALSE;
    int attempt, num_src;
    const GLchar *shader_src_list[3];
    const GLchar *shader_body = GLES2_GetShader(type);

    if (!shader_body) {
        SDL_SetError("No shader body src");
        return true;
    }

    for (attempt = 0; attempt < 2 && !compileSuccessful; ++attempt) {
        num_src = 0;

        shader_src_list[num_src++] = GLES2_GetShaderPrologue(type);

        if (shader_type == GL_FRAGMENT_SHADER) {
            if (attempt == 0) {
                shader_src_list[num_src++] = GLES2_GetShaderInclude(data->texcoord_precision_hint);
            } else {
                shader_src_list[num_src++] = GLES2_GetShaderInclude(GLES2_SHADER_FRAGMENT_INCLUDE_UNDEF_PRECISION);
            }
        }

        shader_src_list[num_src++] = shader_body;

        SDL_assert(num_src <= SDL_arraysize(shader_src_list));

#ifdef DEBUG_PRINT_SHADERS
        {
            int i;
            char *message = NULL;

            SDL_asprintf(&message, "Compiling shader:\n");
            for (i = 0; i < num_src; ++i) {
                char *last_message = message;
                SDL_asprintf(&message, "%s%s", last_message, shader_src_list[i]);
                SDL_free(last_message);
            }
            SDL_Log("%s\n", message);
            SDL_free(message);
        }
#endif

        // Compile
        id = data->glCreateShader(shader_type);
        data->glShaderSource(id, num_src, shader_src_list, NULL);
        data->glCompileShader(id);
        data->glGetShaderiv(id, GL_COMPILE_STATUS, &compileSuccessful);
    }

    if (!compileSuccessful) {
        char *info = NULL;
        int length = 0;

        data->glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        if (length > 0) {
            info = (char *)SDL_malloc(length);
            if (info) {
                data->glGetShaderInfoLog(id, length, &length, info);
            }
        }
        if (info) {
            SDL_SetError("Failed to load the shader %d: %s", type, info);
            SDL_free(info);
        } else {
            SDL_SetError("Failed to load the shader %d", type);
        }
        data->glDeleteShader(id);
        return true;
    }

    // Cache
    data->shader_id_cache[(Uint32)type] = id;

    return id;
}

static bool GLES2_CacheShaders(GLES2_RenderData *data)
{
    int shader;

    data->texcoord_precision_hint = GLES2_GetTexCoordPrecisionEnumFromHint();

    for (shader = 0; shader < GLES2_SHADER_FRAGMENT_TEXTURE_EXTERNAL_OES; ++shader) {
        GLenum shader_type;

        if (shader == GLES2_SHADER_VERTEX_DEFAULT) {
            shader_type = GL_VERTEX_SHADER;
        } else {
            shader_type = GL_FRAGMENT_SHADER;
        }
        if (!GLES2_CacheShader(data, (GLES2_ShaderType)shader, shader_type)) {
            return false;
        }
    }
    return true;
}

static bool GLES2_SelectProgram(GLES2_RenderData *data, GLES2_ImageSource source, SDL_Colorspace colorspace)
{
    GLuint vertex;
    GLuint fragment;
    GLES2_ShaderType vtype, ftype;
    GLES2_ProgramCacheEntry *program;
    const float *shader_params = NULL;

    // Select an appropriate shader pair for the specified modes
    vtype = GLES2_SHADER_VERTEX_DEFAULT;
    switch (source) {
    case GLES2_IMAGESOURCE_SOLID:
        ftype = GLES2_SHADER_FRAGMENT_SOLID;
        break;
    case GLES2_IMAGESOURCE_TEXTURE_ABGR:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_ABGR;
        break;
    case GLES2_IMAGESOURCE_TEXTURE_ARGB:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_ARGB;
        break;
    case GLES2_IMAGESOURCE_TEXTURE_RGB:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_RGB;
        break;
    case GLES2_IMAGESOURCE_TEXTURE_BGR:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_BGR;
        break;
#ifdef SDL_HAVE_YUV
    case GLES2_IMAGESOURCE_TEXTURE_YUV:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_YUV;
        shader_params = SDL_GetYCbCRtoRGBConversionMatrix(colorspace, 0, 0, 8);
        if (!shader_params) {
            SDL_SetError("Unsupported YUV colorspace");
            goto fault;
        }
        break;
    case GLES2_IMAGESOURCE_TEXTURE_NV12:
        if (SDL_GetHintBoolean("SDL_RENDER_OPENGL_NV12_RG_SHADER", false)) {
            ftype = GLES2_SHADER_FRAGMENT_TEXTURE_NV12_RG;
        } else {
            ftype = GLES2_SHADER_FRAGMENT_TEXTURE_NV12_RA;
        }
        shader_params = SDL_GetYCbCRtoRGBConversionMatrix(colorspace, 0, 0, 8);
        if (!shader_params) {
            SDL_SetError("Unsupported YUV colorspace");
            goto fault;
        }
        break;
    case GLES2_IMAGESOURCE_TEXTURE_NV21:
        if (SDL_GetHintBoolean("SDL_RENDER_OPENGL_NV12_RG_SHADER", false)) {
            ftype = GLES2_SHADER_FRAGMENT_TEXTURE_NV21_RG;
        } else {
            ftype = GLES2_SHADER_FRAGMENT_TEXTURE_NV21_RA;
        }
        shader_params = SDL_GetYCbCRtoRGBConversionMatrix(colorspace, 0, 0, 8);
        if (!shader_params) {
            SDL_SetError("Unsupported YUV colorspace");
            goto fault;
        }
        break;
#endif // SDL_HAVE_YUV
    case GLES2_IMAGESOURCE_TEXTURE_EXTERNAL_OES:
        ftype = GLES2_SHADER_FRAGMENT_TEXTURE_EXTERNAL_OES;
        break;
    default:
        goto fault;
    }

    // Load the requested shaders
    vertex = data->shader_id_cache[(Uint32)vtype];
    if (!vertex) {
        vertex = GLES2_CacheShader(data, vtype, GL_VERTEX_SHADER);
        if (!vertex) {
            goto fault;
        }
    }

    fragment = data->shader_id_cache[(Uint32)ftype];
    if (!fragment) {
        fragment = GLES2_CacheShader(data, ftype, GL_FRAGMENT_SHADER);
        if (!fragment) {
            goto fault;
        }
    }

    // Check if we need to change programs at all
    if (data->drawstate.program &&
        data->drawstate.program->vertex_shader == vertex &&
        data->drawstate.program->fragment_shader == fragment &&
        data->drawstate.program->shader_params == shader_params) {
        return true;
    }

    // Generate a matching program
    program = GLES2_CacheProgram(data, vertex, fragment);
    if (!program) {
        goto fault;
    }

    // Select that program in OpenGL
    data->glUseProgram(program->id);

    if (shader_params && shader_params != program->shader_params) {
        // YUV shader params are Yoffset, 0, Rcoeff, 0, Gcoeff, 0, Bcoeff, 0
        if (program->uniform_locations[GLES2_UNIFORM_OFFSET] != -1) {
            data->glUniform3f(program->uniform_locations[GLES2_UNIFORM_OFFSET], shader_params[0], shader_params[1], shader_params[2]);
        }
        if (program->uniform_locations[GLES2_UNIFORM_MATRIX] != -1) {
            GLfloat matrix[3 * 3];

            matrix[0 * 3 + 0] = shader_params[4];
            matrix[0 * 3 + 1] = shader_params[5];
            matrix[0 * 3 + 2] = shader_params[6];
            matrix[1 * 3 + 0] = shader_params[8];
            matrix[1 * 3 + 1] = shader_params[9];
            matrix[1 * 3 + 2] = shader_params[10];
            matrix[2 * 3 + 0] = shader_params[12];
            matrix[2 * 3 + 1] = shader_params[13];
            matrix[2 * 3 + 2] = shader_params[14];
            data->glUniformMatrix3fv(program->uniform_locations[GLES2_UNIFORM_MATRIX], 1, GL_FALSE, matrix);
        }
        program->shader_params = shader_params;
    }

    // Set the current program
    data->drawstate.program = program;

    // Clean up and return
    return true;
fault:
    data->drawstate.program = NULL;
    return false;
}

static bool GLES2_QueueNoOp(SDL_Renderer *renderer, SDL_RenderCommand *cmd)
{
    return true; // nothing to do in this backend.
}

static bool GLES2_QueueDrawPoints(SDL_Renderer *renderer, SDL_RenderCommand *cmd, const SDL_FPoint *points, int count)
{
    const bool colorswap = (renderer->target && (renderer->target->format == SDL_PIXELFORMAT_BGRA32 || renderer->target->format == SDL_PIXELFORMAT_BGRX32));
    SDL_VertexSolid *verts = (SDL_VertexSolid *)SDL_AllocateRenderVertices(renderer, count * sizeof(*verts), 0, &cmd->data.draw.first);
    int i;
    SDL_FColor color = cmd->data.draw.color;
    const float color_scale = cmd->data.draw.color_scale;

    if (!verts) {
        return false;
    }

    color.r *= color_scale;
    color.g *= color_scale;
    color.b *= color_scale;

    if (colorswap) {
        float r = color.r;
        color.r = color.b;
        color.b = r;
    }

    cmd->data.draw.count = count;
    for (i = 0; i < count; i++) {
        verts->position.x = 0.5f + points[i].x;
        verts->position.y = 0.5f + points[i].y;
        verts->color = color;
        verts++;
    }

    return true;
}

static bool GLES2_QueueDrawLines(SDL_Renderer *renderer, SDL_RenderCommand *cmd, const SDL_FPoint *points, int count)
{
    const bool colorswap = (renderer->target && (renderer->target->format == SDL_PIXELFORMAT_BGRA32 || renderer->target->format == SDL_PIXELFORMAT_BGRX32));
    int i;
    GLfloat prevx, prevy;
    SDL_VertexSolid *verts = (SDL_VertexSolid *)SDL_AllocateRenderVertices(renderer, count * sizeof(*verts), 0, &cmd->data.draw.first);
    SDL_FColor color = cmd->data.draw.color;
    const float color_scale = cmd->data.draw.color_scale;

    if (!verts) {
        return false;
    }

    color.r *= color_scale;
    color.g *= color_scale;
    color.b *= color_scale;

    if (colorswap) {
        float r = color.r;
        color.r = color.b;
        color.b = r;
    }

    cmd->data.draw.count = count;

    // 0.5f offset to hit the center of the pixel.
    prevx = 0.5f + points->x;
    prevy = 0.5f + points->y;
    verts->position.x = prevx;
    verts->position.y = prevy;
    verts->color = color;
    verts++;

    /* bump the end of each line segment out a quarter of a pixel, to provoke
       the diamond-exit rule. Without this, you won't just drop the last
       pixel of the last line segment, but you might also drop pixels at the
       edge of any given line segment along the way too. */
    for (i = 1; i < count; i++) {
        const GLfloat xstart = prevx;
        const GLfloat ystart = prevy;
        const GLfloat xend = points[i].x + 0.5f; // 0.5f to hit pixel center.
        const GLfloat yend = points[i].y + 0.5f;
        // bump a little in the direction we are moving in.
        const GLfloat deltax = xend - xstart;
        const GLfloat deltay = yend - ystart;
        const GLfloat angle = SDL_atan2f(deltay, deltax);
        prevx = xend + (SDL_cosf(angle) * 0.25f);
        prevy = yend + (SDL_sinf(angle) * 0.25f);
        verts->position.x = prevx;
        verts->position.y = prevy;
        verts->color = color;
        verts++;
    }

    return true;
}

static bool GLES2_QueueGeometry(SDL_Renderer *renderer, SDL_RenderCommand *cmd, SDL_Texture *texture,
                               const float *xy, int xy_stride, const SDL_FColor *color, int color_stride, const float *uv, int uv_stride,
                               int num_vertices, const void *indices, int num_indices, int size_indices,
                               float scale_x, float scale_y)
{
    int i;
    const bool colorswap = (renderer->target && (renderer->target->format == SDL_PIXELFORMAT_BGRA32 || renderer->target->format == SDL_PIXELFORMAT_BGRX32));
    int count = indices ? num_indices : num_vertices;
    const float color_scale = cmd->data.draw.color_scale;

    cmd->data.draw.count = count;
    size_indices = indices ? size_indices : 0;

    if (texture) {
        SDL_Vertex *verts = (SDL_Vertex *)SDL_AllocateRenderVertices(renderer, count * sizeof(*verts), 0, &cmd->data.draw.first);
        if (!verts) {
            return false;
        }

        for (i = 0; i < count; i++) {
            int j;
            float *xy_;
            SDL_FColor col_;
            float *uv_;
            if (size_indices == 4) {
                j = ((const Uint32 *)indices)[i];
            } else if (size_indices == 2) {
                j = ((const Uint16 *)indices)[i];
            } else if (size_indices == 1) {
                j = ((const Uint8 *)indices)[i];
            } else {
                j = i;
            }

            xy_ = (float *)((char *)xy + j * xy_stride);
            col_ = *(SDL_FColor *)((char *)color + j * color_stride);
            uv_ = (float *)((char *)uv + j * uv_stride);

            verts->position.x = xy_[0] * scale_x;
            verts->position.y = xy_[1] * scale_y;

            col_.r *= color_scale;
            col_.g *= color_scale;
            col_.b *= color_scale;

            if (colorswap) {
                float r = col_.r;
                col_.r = col_.b;
                col_.b = r;
            }

            verts->color = col_;
            verts->tex_coord.x = uv_[0];
            verts->tex_coord.y = uv_[1];
            verts++;
        }

    } else {
        SDL_VertexSolid *verts = (SDL_VertexSolid *)SDL_AllocateRenderVertices(renderer, count * sizeof(*verts), 0, &cmd->data.draw.first);
        if (!verts) {
            return false;
        }

        for (i = 0; i < count; i++) {
            int j;
            float *xy_;
            SDL_FColor col_;

            if (size_indices == 4) {
                j = ((const Uint32 *)indices)[i];
            } else if (size_indices == 2) {
                j = ((const Uint16 *)indices)[i];
            } else if (size_indices == 1) {
                j = ((const Uint8 *)indices)[i];
            } else {
                j = i;
            }

            xy_ = (float *)((char *)xy + j * xy_stride);
            col_ = *(SDL_FColor *)((char *)color + j * color_stride);

            verts->position.x = xy_[0] * scale_x;
            verts->position.y = xy_[1] * scale_y;

            col_.r *= color_scale;
            col_.g *= color_scale;
            col_.b *= color_scale;

            if (colorswap) {
                float r = col_.r;
                col_.r = col_.b;
                col_.b = r;
            }

            verts->color = col_;
            verts++;
        }
    }

    return true;
}

static bool SetDrawState(GLES2_RenderData *data, const SDL_RenderCommand *cmd, const GLES2_ImageSource imgsrc, void *vertices)
{
    SDL_Texture *texture = cmd->data.draw.texture;
    const SDL_BlendMode blend = cmd->data.draw.blend;
    GLES2_ProgramCacheEntry *program;
    int stride;

    SDL_assert((texture != NULL) == (imgsrc != GLES2_IMAGESOURCE_SOLID));

    if (data->drawstate.viewport_dirty) {
        const SDL_Rect *viewport = &data->drawstate.viewport;
        data->glViewport(viewport->x,
                         data->drawstate.target ? viewport->y : (data->drawstate.drawableh - viewport->y - viewport->h),
                         viewport->w, viewport->h);
        if (viewport->w && viewport->h) {
            data->drawstate.projection[0][0] = 2.0f / viewport->w;
            data->drawstate.projection[1][1] = (data->drawstate.target ? 2.0f : -2.0f) / viewport->h;
            data->drawstate.projection[3][1] = data->drawstate.target ? -1.0f : 1.0f;
        }
        data->drawstate.viewport_dirty = false;
    }

    if (data->drawstate.cliprect_enabled_dirty) {
        if (!data->drawstate.cliprect_enabled) {
            data->glDisable(GL_SCISSOR_TEST);
        } else {
            data->glEnable(GL_SCISSOR_TEST);
        }
        data->drawstate.cliprect_enabled_dirty = false;
    }

    if (data->drawstate.cliprect_enabled && data->drawstate.cliprect_dirty) {
        const SDL_Rect *viewport = &data->drawstate.viewport;
        const SDL_Rect *rect = &data->drawstate.cliprect;
        data->glScissor(viewport->x + rect->x,
                        data->drawstate.target ? viewport->y + rect->y : data->drawstate.drawableh - viewport->y - rect->y - rect->h,
                        rect->w, rect->h);
        data->drawstate.cliprect_dirty = false;
    }

    if (data->drawstate.texturing_dirty || ((texture != NULL) != data->drawstate.texturing)) {
        if (!texture) {
            data->glDisableVertexAttribArray((GLenum)GLES2_ATTRIBUTE_TEXCOORD);
            data->drawstate.texturing = false;
        } else {
            data->glEnableVertexAttribArray((GLenum)GLES2_ATTRIBUTE_TEXCOORD);
            data->drawstate.texturing = true;
        }
        data->drawstate.texturing_dirty = false;
    }

    if (texture) {
        stride = sizeof(SDL_Vertex);
    } else {
        stride = sizeof(SDL_VertexSolid);
    }

    if (texture) {
        SDL_Vertex *verts = (SDL_Vertex *)(((Uint8 *)vertices) + cmd->data.draw.first);
        data->glVertexAttribPointer(GLES2_ATTRIBUTE_TEXCOORD, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)&verts->tex_coord);
    }

    if (!GLES2_SelectProgram(data, imgsrc, texture ? texture->colorspace : SDL_COLORSPACE_SRGB)) {
        return false;
    }

    program = data->drawstate.program;

    if (program->uniform_locations[GLES2_UNIFORM_PROJECTION] != -1) {
        if (SDL_memcmp(program->projection, data->drawstate.projection, sizeof(data->drawstate.projection)) != 0) {
            data->glUniformMatrix4fv(program->uniform_locations[GLES2_UNIFORM_PROJECTION], 1, GL_FALSE, (GLfloat *)data->drawstate.projection);
            SDL_memcpy(program->projection, data->drawstate.projection, sizeof(data->drawstate.projection));
        }
    }

    if (blend != data->drawstate.blend) {
        if (blend == SDL_BLENDMODE_NONE) {
            data->glDisable(GL_BLEND);
        } else {
            data->glEnable(GL_BLEND);
            data->glBlendFuncSeparate(GetBlendFunc(SDL_GetBlendModeSrcColorFactor(blend)),
                                      GetBlendFunc(SDL_GetBlendModeDstColorFactor(blend)),
                                      GetBlendFunc(SDL_GetBlendModeSrcAlphaFactor(blend)),
                                      GetBlendFunc(SDL_GetBlendModeDstAlphaFactor(blend)));
            data->glBlendEquationSeparate(GetBlendEquation(SDL_GetBlendModeColorOperation(blend)),
                                          GetBlendEquation(SDL_GetBlendModeAlphaOperation(blend)));
        }
        data->drawstate.blend = blend;
    }

    // all drawing commands use this
    {
        SDL_VertexSolid *verts = (SDL_VertexSolid *)(((Uint8 *)vertices) + cmd->data.draw.first);
        data->glVertexAttribPointer(GLES2_ATTRIBUTE_POSITION, 2, GL_FLOAT, GL_FALSE, stride, (const GLvoid *)&verts->position);
        data->glVertexAttribPointer(GLES2_ATTRIBUTE_COLOR, 4, GL_FLOAT, GL_TRUE /* Normalized */, stride, (const GLvoid *)&verts->color);
    }

    return true;
}

static bool SetTextureAddressMode(GLES2_RenderData *data, GLenum textype, SDL_TextureAddressMode addressMode)
{
    switch (addressMode) {
    case SDL_TEXTURE_ADDRESS_CLAMP:
        data->glTexParameteri(textype, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        data->glTexParameteri(textype, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        break;
    case SDL_TEXTURE_ADDRESS_WRAP:
        data->glTexParameteri(textype, GL_TEXTURE_WRAP_S, GL_REPEAT);
        data->glTexParameteri(textype, GL_TEXTURE_WRAP_T, GL_REPEAT);
        break;
    default:
        return SDL_SetError("Unknown texture address mode: %d\n", addressMode);
    }
    return true;
}

static bool SetCopyState(SDL_Renderer *renderer, const SDL_RenderCommand *cmd, void *vertices)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_ImageSource sourceType = GLES2_IMAGESOURCE_TEXTURE_ABGR;
    SDL_Texture *texture = cmd->data.draw.texture;
    int ret;

    // Pick an appropriate shader
    if (renderer->target) {
        // Check if we need to do color mapping between the source and render target textures
        if (renderer->target->format != texture->format) {
            switch (texture->format) {
            case SDL_PIXELFORMAT_BGRA32:
                switch (renderer->target->format) {
                case SDL_PIXELFORMAT_RGBA32:
                case SDL_PIXELFORMAT_RGBX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
                    break;
                case SDL_PIXELFORMAT_BGRX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ABGR;
                    break;
                default:
                    break;
                }
                break;
            case SDL_PIXELFORMAT_RGBA32:
                switch (renderer->target->format) {
                case SDL_PIXELFORMAT_BGRA32:
                case SDL_PIXELFORMAT_BGRX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
                    break;
                case SDL_PIXELFORMAT_RGBX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ABGR;
                    break;
                default:
                    break;
                }
                break;
            case SDL_PIXELFORMAT_BGRX32:
                switch (renderer->target->format) {
                case SDL_PIXELFORMAT_RGBA32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
                    break;
                case SDL_PIXELFORMAT_BGRA32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_BGR;
                    break;
                case SDL_PIXELFORMAT_RGBX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
                    break;
                default:
                    break;
                }
                break;
            case SDL_PIXELFORMAT_RGBX32:
                switch (renderer->target->format) {
                case SDL_PIXELFORMAT_RGBA32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_BGR;
                    break;
                case SDL_PIXELFORMAT_BGRA32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_RGB;
                    break;
                case SDL_PIXELFORMAT_BGRX32:
                    sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
                    break;
                default:
                    break;
                }
                break;
#ifdef SDL_HAVE_YUV
            case SDL_PIXELFORMAT_IYUV:
            case SDL_PIXELFORMAT_YV12:
                sourceType = GLES2_IMAGESOURCE_TEXTURE_YUV;
                break;
            case SDL_PIXELFORMAT_NV12:
                sourceType = GLES2_IMAGESOURCE_TEXTURE_NV12;
                break;
            case SDL_PIXELFORMAT_NV21:
                sourceType = GLES2_IMAGESOURCE_TEXTURE_NV21;
                break;
#endif
            case SDL_PIXELFORMAT_EXTERNAL_OES:
                sourceType = GLES2_IMAGESOURCE_TEXTURE_EXTERNAL_OES;
                break;
            default:
                return SDL_SetError("Unsupported texture format");
            }
        } else {
            sourceType = GLES2_IMAGESOURCE_TEXTURE_ABGR; // Texture formats match, use the non color mapping shader (even if the formats are not ABGR)
        }
    } else {
        switch (texture->format) {
        case SDL_PIXELFORMAT_BGRA32:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_ARGB;
            break;
        case SDL_PIXELFORMAT_RGBA32:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_ABGR;
            break;
        case SDL_PIXELFORMAT_BGRX32:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_RGB;
            break;
        case SDL_PIXELFORMAT_RGBX32:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_BGR;
            break;
#ifdef SDL_HAVE_YUV
        case SDL_PIXELFORMAT_IYUV:
        case SDL_PIXELFORMAT_YV12:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_YUV;
            break;
        case SDL_PIXELFORMAT_NV12:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_NV12;
            break;
        case SDL_PIXELFORMAT_NV21:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_NV21;
            break;
#endif
        case SDL_PIXELFORMAT_EXTERNAL_OES:
            sourceType = GLES2_IMAGESOURCE_TEXTURE_EXTERNAL_OES;
            break;
        default:
            return SDL_SetError("Unsupported texture format");
        }
    }

    ret = SetDrawState(data, cmd, sourceType, vertices);

    if (texture != data->drawstate.texture) {
        GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;
#ifdef SDL_HAVE_YUV
        if (tdata->yuv) {
            data->glActiveTexture(GL_TEXTURE2);
            data->glBindTexture(tdata->texture_type, tdata->texture_v);

            if (!SetTextureAddressMode(data, tdata->texture_type, cmd->data.draw.texture_address_mode)) {
                return false;
            }

            data->glActiveTexture(GL_TEXTURE1);
            data->glBindTexture(tdata->texture_type, tdata->texture_u);

            if (!SetTextureAddressMode(data, tdata->texture_type, cmd->data.draw.texture_address_mode)) {
                return false;
            }

            data->glActiveTexture(GL_TEXTURE0);
        } else if (tdata->nv12) {
            data->glActiveTexture(GL_TEXTURE1);
            data->glBindTexture(tdata->texture_type, tdata->texture_u);

            if (!SetTextureAddressMode(data, tdata->texture_type, cmd->data.draw.texture_address_mode)) {
                return false;
            }

            data->glActiveTexture(GL_TEXTURE0);
        }
#endif
        data->glBindTexture(tdata->texture_type, tdata->texture);

        if (!SetTextureAddressMode(data, tdata->texture_type, cmd->data.draw.texture_address_mode)) {
            return false;
        }

        data->drawstate.texture = texture;
    }

    return ret;
}

static void GLES2_InvalidateCachedState(SDL_Renderer *renderer)
{
    GLES2_DrawStateCache *cache = &((GLES2_RenderData *)renderer->internal)->drawstate;
    cache->viewport_dirty = true;
    cache->texture = NULL;
    cache->blend = SDL_BLENDMODE_INVALID;
    cache->cliprect_enabled_dirty = true;
    cache->cliprect_dirty = true;
    cache->texturing_dirty = true;
    cache->clear_color_dirty = true;
    cache->drawablew = 0;
    cache->drawableh = 0;
    cache->program = NULL;
}

static bool GLES2_RunCommandQueue(SDL_Renderer *renderer, SDL_RenderCommand *cmd, void *vertices, size_t vertsize)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    const bool colorswap = (renderer->target && (renderer->target->format == SDL_PIXELFORMAT_BGRA32 || renderer->target->format == SDL_PIXELFORMAT_BGRX32));

#if USE_VERTEX_BUFFER_OBJECTS
    const int vboidx = data->current_vertex_buffer;
    const GLuint vbo = data->vertex_buffers[vboidx];
#endif

    if (!GLES2_ActivateRenderer(renderer)) {
        return false;
    }

    data->drawstate.target = renderer->target;
    if (!data->drawstate.target) {
        int w, h;
        SDL_GetWindowSizeInPixels(renderer->window, &w, &h);
        if ((w != data->drawstate.drawablew) || (h != data->drawstate.drawableh)) {
            data->drawstate.viewport_dirty = true; // if the window dimensions changed, invalidate the current viewport, etc.
            data->drawstate.cliprect_dirty = true;
            data->drawstate.drawablew = w;
            data->drawstate.drawableh = h;
        }
    }

#if USE_VERTEX_BUFFER_OBJECTS
    // upload the new VBO data for this set of commands.
    data->glBindBuffer(GL_ARRAY_BUFFER, vbo);
    if (data->vertex_buffer_size[vboidx] < vertsize) {
        data->glBufferData(GL_ARRAY_BUFFER, vertsize, vertices, GL_STREAM_DRAW);
        data->vertex_buffer_size[vboidx] = vertsize;
    } else {
        data->glBufferSubData(GL_ARRAY_BUFFER, 0, vertsize, vertices);
    }

    // cycle through a few VBOs so the GL has some time with the data before we replace it.
    data->current_vertex_buffer++;
    if (data->current_vertex_buffer >= SDL_arraysize(data->vertex_buffers)) {
        data->current_vertex_buffer = 0;
    }
    vertices = NULL; // attrib pointers will be offsets into the VBO.
#endif

    while (cmd) {
        switch (cmd->command) {
        case SDL_RENDERCMD_SETDRAWCOLOR:
        {
            break;
        }

        case SDL_RENDERCMD_SETVIEWPORT:
        {
            SDL_Rect *viewport = &data->drawstate.viewport;
            if (SDL_memcmp(viewport, &cmd->data.viewport.rect, sizeof(cmd->data.viewport.rect)) != 0) {
                SDL_copyp(viewport, &cmd->data.viewport.rect);
                data->drawstate.viewport_dirty = true;
                data->drawstate.cliprect_dirty = true;
            }
            break;
        }

        case SDL_RENDERCMD_SETCLIPRECT:
        {
            const SDL_Rect *rect = &cmd->data.cliprect.rect;
            if (data->drawstate.cliprect_enabled != cmd->data.cliprect.enabled) {
                data->drawstate.cliprect_enabled = cmd->data.cliprect.enabled;
                data->drawstate.cliprect_enabled_dirty = true;
            }

            if (SDL_memcmp(&data->drawstate.cliprect, rect, sizeof(*rect)) != 0) {
                SDL_copyp(&data->drawstate.cliprect, rect);
                data->drawstate.cliprect_dirty = true;
            }
            break;
        }

        case SDL_RENDERCMD_CLEAR:
        {
            const float r = (colorswap ? cmd->data.color.color.b : cmd->data.color.color.r) * cmd->data.color.color_scale;
            const float g = cmd->data.color.color.g * cmd->data.color.color_scale;
            const float b = (colorswap ? cmd->data.color.color.r : cmd->data.color.color.b) * cmd->data.color.color_scale;
            const float a = cmd->data.color.color.a;
            if (data->drawstate.clear_color_dirty ||
                (r != data->drawstate.clear_color.r) ||
                (g != data->drawstate.clear_color.g) ||
                (b != data->drawstate.clear_color.b) ||
                (a != data->drawstate.clear_color.a)) {
                data->glClearColor(r, g, b, a);
                data->drawstate.clear_color.r = r;
                data->drawstate.clear_color.g = g;
                data->drawstate.clear_color.b = b;
                data->drawstate.clear_color.a = a;
                data->drawstate.clear_color_dirty = false;
            }

            if (data->drawstate.cliprect_enabled || data->drawstate.cliprect_enabled_dirty) {
                data->glDisable(GL_SCISSOR_TEST);
                data->drawstate.cliprect_enabled_dirty = data->drawstate.cliprect_enabled;
            }

            data->glClear(GL_COLOR_BUFFER_BIT);
            break;
        }

        case SDL_RENDERCMD_FILL_RECTS: // unused
            break;

        case SDL_RENDERCMD_COPY: // unused
            break;

        case SDL_RENDERCMD_COPY_EX: // unused
            break;

        case SDL_RENDERCMD_DRAW_LINES:
        {
            if (SetDrawState(data, cmd, GLES2_IMAGESOURCE_SOLID, vertices)) {
                size_t count = cmd->data.draw.count;
                if (count > 2) {
                    // joined lines cannot be grouped
                    data->glDrawArrays(GL_LINE_STRIP, 0, (GLsizei)count);
                } else {
                    // let's group non joined lines
                    SDL_RenderCommand *finalcmd = cmd;
                    SDL_RenderCommand *nextcmd = cmd->next;
                    SDL_BlendMode thisblend = cmd->data.draw.blend;

                    while (nextcmd) {
                        const SDL_RenderCommandType nextcmdtype = nextcmd->command;
                        if (nextcmdtype != SDL_RENDERCMD_DRAW_LINES) {
                            break; // can't go any further on this draw call, different render command up next.
                        } else if (nextcmd->data.draw.count != 2) {
                            break; // can't go any further on this draw call, those are joined lines
                        } else if (nextcmd->data.draw.blend != thisblend) {
                            break; // can't go any further on this draw call, different blendmode copy up next.
                        } else {
                            finalcmd = nextcmd; // we can combine copy operations here. Mark this one as the furthest okay command.
                            count += nextcmd->data.draw.count;
                        }
                        nextcmd = nextcmd->next;
                    }

                    data->glDrawArrays(GL_LINES, 0, (GLsizei)count);
                    cmd = finalcmd; // skip any copy commands we just combined in here.
                }
            }
            break;
        }

        case SDL_RENDERCMD_DRAW_POINTS:
        case SDL_RENDERCMD_GEOMETRY:
        {
            /* as long as we have the same copy command in a row, with the
               same texture, we can combine them all into a single draw call. */
            SDL_Texture *thistexture = cmd->data.draw.texture;
            SDL_BlendMode thisblend = cmd->data.draw.blend;
            const SDL_RenderCommandType thiscmdtype = cmd->command;
            SDL_RenderCommand *finalcmd = cmd;
            SDL_RenderCommand *nextcmd = cmd->next;
            size_t count = cmd->data.draw.count;
            int ret;
            while (nextcmd) {
                const SDL_RenderCommandType nextcmdtype = nextcmd->command;
                if (nextcmdtype != thiscmdtype) {
                    break; // can't go any further on this draw call, different render command up next.
                } else if (nextcmd->data.draw.texture != thistexture || nextcmd->data.draw.blend != thisblend) {
                    break; // can't go any further on this draw call, different texture/blendmode copy up next.
                } else {
                    finalcmd = nextcmd; // we can combine copy operations here. Mark this one as the furthest okay command.
                    count += nextcmd->data.draw.count;
                }
                nextcmd = nextcmd->next;
            }

            if (thistexture) {
                ret = SetCopyState(renderer, cmd, vertices);
            } else {
                ret = SetDrawState(data, cmd, GLES2_IMAGESOURCE_SOLID, vertices);
            }

            if (ret) {
                int op = GL_TRIANGLES; // SDL_RENDERCMD_GEOMETRY
                if (thiscmdtype == SDL_RENDERCMD_DRAW_POINTS) {
                    op = GL_POINTS;
                }
                data->glDrawArrays(op, 0, (GLsizei)count);
            }

            cmd = finalcmd; // skip any copy commands we just combined in here.
            break;
        }

        case SDL_RENDERCMD_NO_OP:
            break;
        }

        cmd = cmd->next;
    }

    return GL_CheckError("", renderer);
}

static void GLES2_DestroyRenderer(SDL_Renderer *renderer)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;

    // Deallocate everything
    if (data) {
        GLES2_ActivateRenderer(renderer);

        {
            int i;
            for (i = 0; i < GLES2_SHADER_COUNT; i++) {
                GLuint id = data->shader_id_cache[i];
                if (id) {
                    data->glDeleteShader(id);
                }
            }
        }
        {
            GLES2_ProgramCacheEntry *entry;
            GLES2_ProgramCacheEntry *next;
            entry = data->program_cache.head;
            while (entry) {
                data->glDeleteProgram(entry->id);
                next = entry->next;
                SDL_free(entry);
                entry = next;
            }
        }

        if (data->context) {
            while (data->framebuffers) {
                GLES2_FBOList *nextnode = data->framebuffers->next;
                data->glDeleteFramebuffers(1, &data->framebuffers->FBO);
                GL_CheckError("", renderer);
                SDL_free(data->framebuffers);
                data->framebuffers = nextnode;
            }

#if USE_VERTEX_BUFFER_OBJECTS
            data->glDeleteBuffers(SDL_arraysize(data->vertex_buffers), data->vertex_buffers);
            GL_CheckError("", renderer);
#endif

            SDL_GL_DestroyContext(data->context);
        }

        SDL_free(data);
    }
}

static bool GLES2_CreateTexture(SDL_Renderer *renderer, SDL_Texture *texture, SDL_PropertiesID create_props)
{
    GLES2_RenderData *renderdata = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *data;
    GLenum format;
    GLenum type;
    GLenum scaleMode;

    GLES2_ActivateRenderer(renderer);

    renderdata->drawstate.texture = NULL; // we trash this state.

    // Determine the corresponding GLES texture format params
    switch (texture->format) {
    case SDL_PIXELFORMAT_BGRA32:
    case SDL_PIXELFORMAT_RGBA32:
    case SDL_PIXELFORMAT_BGRX32:
    case SDL_PIXELFORMAT_RGBX32:
        format = GL_RGBA;
        type = GL_UNSIGNED_BYTE;
        break;
#ifdef SDL_HAVE_YUV
    case SDL_PIXELFORMAT_IYUV:
    case SDL_PIXELFORMAT_YV12:
    case SDL_PIXELFORMAT_NV12:
    case SDL_PIXELFORMAT_NV21:
        format = GL_LUMINANCE;
        type = GL_UNSIGNED_BYTE;
        break;
#endif
#ifdef GL_TEXTURE_EXTERNAL_OES
    case SDL_PIXELFORMAT_EXTERNAL_OES:
        format = GL_NONE;
        type = GL_NONE;
        break;
#endif
    default:
        return SDL_SetError("Texture format not supported");
    }

    if (texture->format == SDL_PIXELFORMAT_EXTERNAL_OES &&
        texture->access != SDL_TEXTUREACCESS_STATIC) {
        return SDL_SetError("Unsupported texture access for SDL_PIXELFORMAT_EXTERNAL_OES");
    }

    // Allocate a texture struct
    data = (GLES2_TextureData *)SDL_calloc(1, sizeof(GLES2_TextureData));
    if (!data) {
        return false;
    }
    data->texture = 0;
#ifdef GL_TEXTURE_EXTERNAL_OES
    data->texture_type = (texture->format == SDL_PIXELFORMAT_EXTERNAL_OES) ? GL_TEXTURE_EXTERNAL_OES : GL_TEXTURE_2D;
#else
    data->texture_type = GL_TEXTURE_2D;
#endif
    data->pixel_format = format;
    data->pixel_type = type;
#ifdef SDL_HAVE_YUV
    data->yuv = ((texture->format == SDL_PIXELFORMAT_IYUV) || (texture->format == SDL_PIXELFORMAT_YV12));
    data->nv12 = ((texture->format == SDL_PIXELFORMAT_NV12) || (texture->format == SDL_PIXELFORMAT_NV21));
    data->texture_u = 0;
    data->texture_v = 0;
#endif
    scaleMode = (texture->scaleMode == SDL_SCALEMODE_NEAREST) ? GL_NEAREST : GL_LINEAR;

    // Allocate a blob for image renderdata
    if (texture->access == SDL_TEXTUREACCESS_STREAMING) {
        size_t size;
        data->pitch = texture->w * SDL_BYTESPERPIXEL(texture->format);
        size = (size_t)texture->h * data->pitch;
#ifdef SDL_HAVE_YUV
        if (data->yuv) {
            // Need to add size for the U and V planes
            size += 2 * ((texture->h + 1) / 2) * ((data->pitch + 1) / 2);
        } else if (data->nv12) {
            // Need to add size for the U/V plane
            size += 2 * ((texture->h + 1) / 2) * ((data->pitch + 1) / 2);
        }
#endif
        data->pixel_data = SDL_calloc(1, size);
        if (!data->pixel_data) {
            SDL_free(data);
            return false;
        }
    }

    // Allocate the texture
    GL_CheckError("", renderer);

#ifdef SDL_HAVE_YUV
    if (data->yuv) {
        data->texture_v = (GLuint)SDL_GetNumberProperty(create_props, SDL_PROP_TEXTURE_CREATE_OPENGLES2_TEXTURE_V_NUMBER, 0);
        if (data->texture_v) {
            data->texture_v_external = true;
        } else {
            renderdata->glGenTextures(1, &data->texture_v);
            if (!GL_CheckError("glGenTexures()", renderer)) {
                return false;
            }
        }
        renderdata->glActiveTexture(GL_TEXTURE2);
        renderdata->glBindTexture(data->texture_type, data->texture_v);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, scaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, scaleMode);
        renderdata->glTexImage2D(data->texture_type, 0, format, (texture->w + 1) / 2, (texture->h + 1) / 2, 0, format, type, NULL);
        SDL_SetNumberProperty(SDL_GetTextureProperties(texture), SDL_PROP_TEXTURE_OPENGLES2_TEXTURE_V_NUMBER, data->texture_v);

        data->texture_u = (GLuint)SDL_GetNumberProperty(create_props, SDL_PROP_TEXTURE_CREATE_OPENGLES2_TEXTURE_U_NUMBER, 0);
        if (data->texture_u) {
            data->texture_u_external = true;
        } else {
            renderdata->glGenTextures(1, &data->texture_u);
            if (!GL_CheckError("glGenTexures()", renderer)) {
                return false;
            }
        }
        renderdata->glActiveTexture(GL_TEXTURE1);
        renderdata->glBindTexture(data->texture_type, data->texture_u);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, scaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, scaleMode);
        renderdata->glTexImage2D(data->texture_type, 0, format, (texture->w + 1) / 2, (texture->h + 1) / 2, 0, format, type, NULL);
        if (!GL_CheckError("glTexImage2D()", renderer)) {
            return false;
        }
        SDL_SetNumberProperty(SDL_GetTextureProperties(texture), SDL_PROP_TEXTURE_OPENGLES2_TEXTURE_U_NUMBER, data->texture_u);

        if (!SDL_GetYCbCRtoRGBConversionMatrix(texture->colorspace, texture->w, texture->h, 8)) {
            return SDL_SetError("Unsupported YUV colorspace");
        }
    } else if (data->nv12) {
        data->texture_u = (GLuint)SDL_GetNumberProperty(create_props, SDL_PROP_TEXTURE_CREATE_OPENGLES2_TEXTURE_UV_NUMBER, 0);
        if (data->texture_u) {
            data->texture_u_external = true;
        } else {
            renderdata->glGenTextures(1, &data->texture_u);
            if (!GL_CheckError("glGenTexures()", renderer)) {
                return false;
            }
        }
        renderdata->glActiveTexture(GL_TEXTURE1);
        renderdata->glBindTexture(data->texture_type, data->texture_u);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, scaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, scaleMode);
        renderdata->glTexImage2D(data->texture_type, 0, GL_LUMINANCE_ALPHA, (texture->w + 1) / 2, (texture->h + 1) / 2, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE, NULL);
        if (!GL_CheckError("glTexImage2D()", renderer)) {
            return false;
        }
        SDL_SetNumberProperty(SDL_GetTextureProperties(texture), SDL_PROP_TEXTURE_OPENGLES2_TEXTURE_UV_NUMBER, data->texture_u);

        if (!SDL_GetYCbCRtoRGBConversionMatrix(texture->colorspace, texture->w, texture->h, 8)) {
            return SDL_SetError("Unsupported YUV colorspace");
        }
    }
#endif

    data->texture = (GLuint)SDL_GetNumberProperty(create_props, SDL_PROP_TEXTURE_CREATE_OPENGLES2_TEXTURE_NUMBER, 0);
    if (data->texture) {
        data->texture_external = true;
    } else {
        renderdata->glGenTextures(1, &data->texture);
        if (!GL_CheckError("glGenTexures()", renderer)) {
            return false;
        }
    }
    texture->internal = data;
    renderdata->glActiveTexture(GL_TEXTURE0);
    renderdata->glBindTexture(data->texture_type, data->texture);
    renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, scaleMode);
    renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, scaleMode);
    if (texture->format != SDL_PIXELFORMAT_EXTERNAL_OES) {
        renderdata->glTexImage2D(data->texture_type, 0, format, texture->w, texture->h, 0, format, type, NULL);
        if (!GL_CheckError("glTexImage2D()", renderer)) {
            return false;
        }
    }
    SDL_SetNumberProperty(SDL_GetTextureProperties(texture), SDL_PROP_TEXTURE_OPENGLES2_TEXTURE_NUMBER, data->texture);
    SDL_SetNumberProperty(SDL_GetTextureProperties(texture), SDL_PROP_TEXTURE_OPENGLES2_TEXTURE_TARGET_NUMBER, data->texture_type);

    if (texture->access == SDL_TEXTUREACCESS_TARGET) {
        data->fbo = GLES2_GetFBO((GLES2_RenderData *)renderer->internal, texture->w, texture->h);
    } else {
        data->fbo = NULL;
    }

    return GL_CheckError("", renderer);
}

static bool GLES2_TexSubImage2D(GLES2_RenderData *data, GLenum target, GLint xoffset, GLint yoffset, GLsizei width, GLsizei height, GLenum format, GLenum type, const GLvoid *pixels, GLint pitch, GLint bpp)
{
    Uint8 *blob = NULL;
    Uint8 *src;
    size_t src_pitch;
    int y;

    if ((width == 0) || (height == 0) || (bpp == 0)) {
        return true; // nothing to do
    }

    // Reformat the texture data into a tightly packed array
    src_pitch = (size_t)width * bpp;
    src = (Uint8 *)pixels;
    if ((size_t)pitch != src_pitch) {
        blob = (Uint8 *)SDL_malloc(src_pitch * height);
        if (!blob) {
            return false;
        }
        src = blob;
        for (y = 0; y < height; ++y) {
            SDL_memcpy(src, pixels, src_pitch);
            src += src_pitch;
            pixels = (Uint8 *)pixels + pitch;
        }
        src = blob;
    }

    data->glTexSubImage2D(target, 0, xoffset, yoffset, width, height, format, type, src);
    if (blob) {
        SDL_free(blob);
    }
    return true;
}

static bool GLES2_UpdateTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
                               const void *pixels, int pitch)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;

    GLES2_ActivateRenderer(renderer);

    // Bail out if we're supposed to update an empty rectangle
    if (rect->w <= 0 || rect->h <= 0) {
        return true;
    }

    data->drawstate.texture = NULL; // we trash this state.

    // Create a texture subimage with the supplied data
    data->glBindTexture(tdata->texture_type, tdata->texture);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x,
                        rect->y,
                        rect->w,
                        rect->h,
                        tdata->pixel_format,
                        tdata->pixel_type,
                        pixels, pitch, SDL_BYTESPERPIXEL(texture->format));

#ifdef SDL_HAVE_YUV
    if (tdata->yuv) {
        // Skip to the correct offset into the next texture
        pixels = (const void *)((const Uint8 *)pixels + rect->h * pitch);
        if (texture->format == SDL_PIXELFORMAT_YV12) {
            data->glBindTexture(tdata->texture_type, tdata->texture_v);
        } else {
            data->glBindTexture(tdata->texture_type, tdata->texture_u);
        }
        GLES2_TexSubImage2D(data, tdata->texture_type,
                            rect->x / 2,
                            rect->y / 2,
                            (rect->w + 1) / 2,
                            (rect->h + 1) / 2,
                            tdata->pixel_format,
                            tdata->pixel_type,
                            pixels, (pitch + 1) / 2, 1);

        // Skip to the correct offset into the next texture
        pixels = (const void *)((const Uint8 *)pixels + ((rect->h + 1) / 2) * ((pitch + 1) / 2));
        if (texture->format == SDL_PIXELFORMAT_YV12) {
            data->glBindTexture(tdata->texture_type, tdata->texture_u);
        } else {
            data->glBindTexture(tdata->texture_type, tdata->texture_v);
        }
        GLES2_TexSubImage2D(data, tdata->texture_type,
                            rect->x / 2,
                            rect->y / 2,
                            (rect->w + 1) / 2,
                            (rect->h + 1) / 2,
                            tdata->pixel_format,
                            tdata->pixel_type,
                            pixels, (pitch + 1) / 2, 1);
    } else if (tdata->nv12) {
        // Skip to the correct offset into the next texture
        pixels = (const void *)((const Uint8 *)pixels + rect->h * pitch);
        data->glBindTexture(tdata->texture_type, tdata->texture_u);
        GLES2_TexSubImage2D(data, tdata->texture_type,
                            rect->x / 2,
                            rect->y / 2,
                            (rect->w + 1) / 2,
                            (rect->h + 1) / 2,
                            GL_LUMINANCE_ALPHA,
                            GL_UNSIGNED_BYTE,
                            pixels, 2 * ((pitch + 1) / 2), 2);
    }
#endif

    return GL_CheckError("glTexSubImage2D()", renderer);
}

#ifdef SDL_HAVE_YUV
static bool GLES2_UpdateTextureYUV(SDL_Renderer *renderer, SDL_Texture *texture,
                                  const SDL_Rect *rect,
                                  const Uint8 *Yplane, int Ypitch,
                                  const Uint8 *Uplane, int Upitch,
                                  const Uint8 *Vplane, int Vpitch)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;

    GLES2_ActivateRenderer(renderer);

    // Bail out if we're supposed to update an empty rectangle
    if (rect->w <= 0 || rect->h <= 0) {
        return true;
    }

    data->drawstate.texture = NULL; // we trash this state.

    data->glBindTexture(tdata->texture_type, tdata->texture_v);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x / 2,
                        rect->y / 2,
                        (rect->w + 1) / 2,
                        (rect->h + 1) / 2,
                        tdata->pixel_format,
                        tdata->pixel_type,
                        Vplane, Vpitch, 1);

    data->glBindTexture(tdata->texture_type, tdata->texture_u);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x / 2,
                        rect->y / 2,
                        (rect->w + 1) / 2,
                        (rect->h + 1) / 2,
                        tdata->pixel_format,
                        tdata->pixel_type,
                        Uplane, Upitch, 1);

    data->glBindTexture(tdata->texture_type, tdata->texture);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x,
                        rect->y,
                        rect->w,
                        rect->h,
                        tdata->pixel_format,
                        tdata->pixel_type,
                        Yplane, Ypitch, 1);

    return GL_CheckError("glTexSubImage2D()", renderer);
}

static bool GLES2_UpdateTextureNV(SDL_Renderer *renderer, SDL_Texture *texture,
                                 const SDL_Rect *rect,
                                 const Uint8 *Yplane, int Ypitch,
                                 const Uint8 *UVplane, int UVpitch)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;

    GLES2_ActivateRenderer(renderer);

    // Bail out if we're supposed to update an empty rectangle
    if (rect->w <= 0 || rect->h <= 0) {
        return true;
    }

    data->drawstate.texture = NULL; // we trash this state.

    data->glBindTexture(tdata->texture_type, tdata->texture_u);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x / 2,
                        rect->y / 2,
                        (rect->w + 1) / 2,
                        (rect->h + 1) / 2,
                        GL_LUMINANCE_ALPHA,
                        GL_UNSIGNED_BYTE,
                        UVplane, UVpitch, 2);

    data->glBindTexture(tdata->texture_type, tdata->texture);
    GLES2_TexSubImage2D(data, tdata->texture_type,
                        rect->x,
                        rect->y,
                        rect->w,
                        rect->h,
                        tdata->pixel_format,
                        tdata->pixel_type,
                        Yplane, Ypitch, 1);

    return GL_CheckError("glTexSubImage2D()", renderer);
}
#endif

static bool GLES2_LockTexture(SDL_Renderer *renderer, SDL_Texture *texture, const SDL_Rect *rect,
                             void **pixels, int *pitch)
{
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;

    // Retrieve the buffer/pitch for the specified region
    *pixels = (Uint8 *)tdata->pixel_data +
              (tdata->pitch * rect->y) +
              (rect->x * SDL_BYTESPERPIXEL(texture->format));
    *pitch = tdata->pitch;

    return true;
}

static void GLES2_UnlockTexture(SDL_Renderer *renderer, SDL_Texture *texture)
{
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;
    SDL_Rect rect;

    // We do whole texture updates, at least for now
    rect.x = 0;
    rect.y = 0;
    rect.w = texture->w;
    rect.h = texture->h;
    GLES2_UpdateTexture(renderer, texture, &rect, tdata->pixel_data, tdata->pitch);
}

static void GLES2_SetTextureScaleMode(SDL_Renderer *renderer, SDL_Texture *texture, SDL_ScaleMode scaleMode)
{
    GLES2_RenderData *renderdata = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *data = (GLES2_TextureData *)texture->internal;
    GLenum glScaleMode = (scaleMode == SDL_SCALEMODE_NEAREST) ? GL_NEAREST : GL_LINEAR;

#ifdef SDL_HAVE_YUV
    if (data->yuv) {
        renderdata->glActiveTexture(GL_TEXTURE2);
        renderdata->glBindTexture(data->texture_type, data->texture_v);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, glScaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, glScaleMode);

        renderdata->glActiveTexture(GL_TEXTURE1);
        renderdata->glBindTexture(data->texture_type, data->texture_u);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, glScaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, glScaleMode);
    } else if (data->nv12) {
        renderdata->glActiveTexture(GL_TEXTURE1);
        renderdata->glBindTexture(data->texture_type, data->texture_u);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, glScaleMode);
        renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, glScaleMode);
    }
#endif

    renderdata->glActiveTexture(GL_TEXTURE0);
    renderdata->glBindTexture(data->texture_type, data->texture);
    renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MIN_FILTER, glScaleMode);
    renderdata->glTexParameteri(data->texture_type, GL_TEXTURE_MAG_FILTER, glScaleMode);
}

static bool GLES2_SetRenderTarget(SDL_Renderer *renderer, SDL_Texture *texture)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *texturedata = NULL;
    GLenum status;

    data->drawstate.viewport_dirty = true;

    if (!texture) {
        data->glBindFramebuffer(GL_FRAMEBUFFER, data->window_framebuffer);
    } else {
        texturedata = (GLES2_TextureData *)texture->internal;
        data->glBindFramebuffer(GL_FRAMEBUFFER, texturedata->fbo->FBO);
        // TODO: check if texture pixel format allows this operation
        data->glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, texturedata->texture_type, texturedata->texture, 0);
        // Check FBO status
        status = data->glCheckFramebufferStatus(GL_FRAMEBUFFER);
        if (status != GL_FRAMEBUFFER_COMPLETE) {
            return SDL_SetError("glFramebufferTexture2D() failed");
        }
    }
    return true;
}

static void GLES2_DestroyTexture(SDL_Renderer *renderer, SDL_Texture *texture)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    GLES2_TextureData *tdata = (GLES2_TextureData *)texture->internal;

    GLES2_ActivateRenderer(renderer);

    if (data->drawstate.texture == texture) {
        data->drawstate.texture = NULL;
    }
    if (data->drawstate.target == texture) {
        data->drawstate.target = NULL;
    }

    // Destroy the texture
    if (tdata) {
        if (tdata->texture && !tdata->texture_external) {
            data->glDeleteTextures(1, &tdata->texture);
        }
#ifdef SDL_HAVE_YUV
        if (tdata->texture_v && !tdata->texture_v_external) {
            data->glDeleteTextures(1, &tdata->texture_v);
        }
        if (tdata->texture_u && !tdata->texture_u_external) {
            data->glDeleteTextures(1, &tdata->texture_u);
        }
#endif
        SDL_free(tdata->pixel_data);
        SDL_free(tdata);
        texture->internal = NULL;
    }
}

static SDL_Surface *GLES2_RenderReadPixels(SDL_Renderer *renderer, const SDL_Rect *rect)
{
    GLES2_RenderData *data = (GLES2_RenderData *)renderer->internal;
    SDL_PixelFormat format = renderer->target ? renderer->target->format : SDL_PIXELFORMAT_RGBA32;
    SDL_Surface *surface;

    surface = SDL_CreateSurface(rect->w, rect->h, format);
    if (!surface) {
        return NULL;
    }

    int y = rect->y;
    if (!renderer->target) {
        int w, h;
        SDL_GetRenderOutputSize(renderer, &w, &h);
        y = (h - y) - rect->h;
    }

    data->glReadPixels(rect->x, y, rect->w, rect->h, GL_RGBA, GL_UNSIGNED_BYTE, surface->pixels);
    if (!GL_CheckError("glReadPixels()", renderer)) {
        SDL_DestroySurface(surface);
        return NULL;
    }

    // Flip the rows to be top-down if necessary
    if (!renderer->target) {
        SDL_FlipSurface(surface, SDL_FLIP_VERTICAL);
    }
    return surface;
}

static bool GLES2_RenderPresent(SDL_Renderer *renderer)
{
    // Tell the video driver to swap buffers
    return SDL_GL_SwapWindow(renderer->window);
}

static bool GLES2_SetVSync(SDL_Renderer *renderer, const int vsync)
{
    int interval = 0;

    if (!SDL_GL_SetSwapInterval(vsync)) {
        return false;
    }

    if (!SDL_GL_GetSwapInterval(&interval)) {
        return false;
    }

    if (interval != vsync) {
        return SDL_Unsupported();
    }
    return true;
}

/*************************************************************************************************
 * Renderer instantiation                                                                        *
 *************************************************************************************************/

static bool GLES2_CreateRenderer(SDL_Renderer *renderer, SDL_Window *window, SDL_PropertiesID create_props)
{
    GLES2_RenderData *data = NULL;
    SDL_WindowFlags window_flags = 0; // -Wconditional-uninitialized
    GLint window_framebuffer;
    GLint value;
    int profile_mask = 0, major = 0, minor = 0;
    bool changed_window = false;

    if (!SDL_GL_GetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, &profile_mask)) {
        goto error;
    }
    if (!SDL_GL_GetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, &major)) {
        goto error;
    }
    if (!SDL_GL_GetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, &minor)) {
        goto error;
    }

    SDL_SyncWindow(window);
    window_flags = SDL_GetWindowFlags(window);

    // OpenGL ES 3.0 is a superset of OpenGL ES 2.0
    if (!(window_flags & SDL_WINDOW_OPENGL) ||
        profile_mask != SDL_GL_CONTEXT_PROFILE_ES || major < RENDERER_CONTEXT_MAJOR) {

        changed_window = true;
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, RENDERER_CONTEXT_MAJOR);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, RENDERER_CONTEXT_MINOR);

        if (!SDL_RecreateWindow(window, (window_flags & ~(SDL_WINDOW_VULKAN | SDL_WINDOW_METAL)) | SDL_WINDOW_OPENGL)) {
            goto error;
        }
    }

    SDL_SetupRendererColorspace(renderer, create_props);

    if (renderer->output_colorspace != SDL_COLORSPACE_SRGB) {
        SDL_SetError("Unsupported output colorspace");
        goto error;
    }

    data = (GLES2_RenderData *)SDL_calloc(1, sizeof(GLES2_RenderData));
    if (!data) {
        goto error;
    }
    renderer->internal = data;
    GLES2_InvalidateCachedState(renderer);
    renderer->window = window;

    renderer->name = GLES2_RenderDriver.name;
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_RGBA32);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_BGRA32);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_BGRX32);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_RGBX32);

    // Create an OpenGL ES 2.0 context
    data->context = SDL_GL_CreateContext(window);
    if (!data->context) {
        goto error;
    }
    if (!SDL_GL_MakeCurrent(window, data->context)) {
        goto error;
    }

    if (!GLES2_LoadFunctions(data)) {
        goto error;
    }

    if (!GLES2_CacheShaders(data)) {
        goto error;
    }

    // Check for debug output support
    if (SDL_GL_GetAttribute(SDL_GL_CONTEXT_FLAGS, &value) &&
        (value & SDL_GL_CONTEXT_DEBUG_FLAG)) {
        data->debug_enabled = true;
    }

    value = 0;
    data->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &value);
    SDL_SetNumberProperty(SDL_GetRendererProperties(renderer), SDL_PROP_RENDERER_MAX_TEXTURE_SIZE_NUMBER, value);

#if USE_VERTEX_BUFFER_OBJECTS
    // we keep a few of these and cycle through them, so data can live for a few frames.
    data->glGenBuffers(SDL_arraysize(data->vertex_buffers), data->vertex_buffers);
#endif

    data->framebuffers = NULL;
    data->glGetIntegerv(GL_FRAMEBUFFER_BINDING, &window_framebuffer);
    data->window_framebuffer = (GLuint)window_framebuffer;

    // Populate the function pointers for the module
    renderer->WindowEvent = GLES2_WindowEvent;
    renderer->SupportsBlendMode = GLES2_SupportsBlendMode;
    renderer->CreateTexture = GLES2_CreateTexture;
    renderer->UpdateTexture = GLES2_UpdateTexture;
#ifdef SDL_HAVE_YUV
    renderer->UpdateTextureYUV = GLES2_UpdateTextureYUV;
    renderer->UpdateTextureNV = GLES2_UpdateTextureNV;
#endif
    renderer->LockTexture = GLES2_LockTexture;
    renderer->UnlockTexture = GLES2_UnlockTexture;
    renderer->SetTextureScaleMode = GLES2_SetTextureScaleMode;
    renderer->SetRenderTarget = GLES2_SetRenderTarget;
    renderer->QueueSetViewport = GLES2_QueueNoOp;
    renderer->QueueSetDrawColor = GLES2_QueueNoOp;
    renderer->QueueDrawPoints = GLES2_QueueDrawPoints;
    renderer->QueueDrawLines = GLES2_QueueDrawLines;
    renderer->QueueGeometry = GLES2_QueueGeometry;
    renderer->InvalidateCachedState = GLES2_InvalidateCachedState;
    renderer->RunCommandQueue = GLES2_RunCommandQueue;
    renderer->RenderReadPixels = GLES2_RenderReadPixels;
    renderer->RenderPresent = GLES2_RenderPresent;
    renderer->DestroyTexture = GLES2_DestroyTexture;
    renderer->DestroyRenderer = GLES2_DestroyRenderer;
    renderer->SetVSync = GLES2_SetVSync;
#ifdef SDL_HAVE_YUV
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_YV12);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_IYUV);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_NV12);
    SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_NV21);
#endif
#ifdef GL_TEXTURE_EXTERNAL_OES
    if (GLES2_CacheShader(data, GLES2_SHADER_FRAGMENT_TEXTURE_EXTERNAL_OES, GL_FRAGMENT_SHADER)) {
        SDL_AddSupportedTextureFormat(renderer, SDL_PIXELFORMAT_EXTERNAL_OES);
    }
#endif

    if (SDL_GL_ExtensionSupported("GL_EXT_blend_minmax")) {
        data->GL_EXT_blend_minmax_supported = true;
    }

    // Set up parameters for rendering
    data->glDisable(GL_DEPTH_TEST);
    data->glDisable(GL_CULL_FACE);
    data->glActiveTexture(GL_TEXTURE0);
    data->glPixelStorei(GL_PACK_ALIGNMENT, 1);
    data->glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

    data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_POSITION);
    data->glEnableVertexAttribArray(GLES2_ATTRIBUTE_COLOR);
    data->glDisableVertexAttribArray(GLES2_ATTRIBUTE_TEXCOORD);

    data->glClearColor(1.0f, 1.0f, 1.0f, 1.0f);

    data->drawstate.clear_color.r = 1.0f;
    data->drawstate.clear_color.g = 1.0f;
    data->drawstate.clear_color.b = 1.0f;
    data->drawstate.clear_color.a = 1.0f;
    data->drawstate.projection[3][0] = -1.0f;
    data->drawstate.projection[3][3] = 1.0f;

    GL_CheckError("", renderer);

    return true;

error:
    if (changed_window) {
        // Uh oh, better try to put it back...
        char *error = SDL_strdup(SDL_GetError());
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, profile_mask);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, major);
        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, minor);
        SDL_RecreateWindow(window, window_flags);
        SDL_SetError("%s", error);
        SDL_free(error);
    }
    return false;
}

SDL_RenderDriver GLES2_RenderDriver = {
    GLES2_CreateRenderer, "opengles2"
};

#endif // SDL_VIDEO_RENDER_OGL_ES2
